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University of British Columbia's Snowstar was one of the teams disqualified from the tether competition due to improper measurements of the tether. Unfortunately, the climber did not actually move either - Image courtesy UBC
Even though no teams were successful in the Space Elevator Games, the future looks promising

None of the teams participating in this year's Space Elevator Games (a subset of the 2006 Wirefly X-Prize Cup) could manage to win the contest, according to event organizers. However, one of the competing teams came extremely close to winning. The University of Saskatchewan Space Design Team – USST – went over the time limit by just seconds, which disqualified the team from winning the $200,000 cash prize.

Teams were required to try and make the climb at a rate of 1 meter per second. The Saskatchewan team was able to scale the 50-meter-long ribbon in 58 seconds, which was just a mere two seconds too late. The team from the University of Saskatchewan is optimistic that they will be back next year ready to win the cash prize. 

Controversy surrounds the ruling as the time would have been good enough for a 60-meter-long ribbon, which the Saskatchewan team intended to originally compete on. Furthermore, price officials determined that the ribbon had stretched under the stresses of the wind and the climber, creating room for interpretation in the prize rulings.  Regardless, the USST climber did not descend back down at the end of its climb which would have been a prize requirement if it had ascended fast enough.

Another challenge saw competitors trying to design and construct a tether strong enough that it would be able to carry an elevator into space. For one portion of the competition, teams were required to submit a pre-designed tether for their climber.  A total of three teams were declared disqualified when their tethers came in at the wrong dimensions.  All teams argued this was due to unforseen stresses on the ribbons.

Details of both controversies are available on the Elevator2010.org blog. 

Since no teams won the $200,000 cash prize in the space elevator or tether test, the prize money will be added to the cash pool for next year's competition in each event.  Each unclaimed prize will continue to cummulate until the pool has reached $600,000.  However, with USST as close as they were, optimists are already expecting the prize to be claimed next year.

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Alternative solutions?
By Hakuryu on 10/24/2006 8:28:28 AM , Rating: 2
I don't understand why they are trying to get a powered device to climb a tether instead of trying to use 'dumb' climbers that are powered from the tether itself.

Like rollercoasters, trains, and NASA's own research into using magnetics to launch ships, wouldn't it make more sense to use a larger tether with this sort of technology? Imagine a large tether with a climber that is propelled by magnetics along the tether to make it move up instead of having it climb under it's own power.

We can't transmit energy, so these things will have to use batteries or fuel. To me it would seem logical to remove that need altogether and have the tether supply energy.




RE: Alternative solutions?
By caboosemoose on 10/24/2006 8:49:39 AM , Rating: 3
Normally I'd agree with that, but in the case of a space elevator, it's not so obvious. For starters, you have the added weight of whatever material you use to transmit the power. That's a significant problem when your talking about miles and miles of cabling. And keeping the weight of the ribbon under control is surely paramount.

Then you have the problem of power losses over the same distance. Overall, I suspect a self-powered vehicle is probably the best option.


RE: Alternative solutions?
By rushfan2006 on 10/24/2006 9:34:54 AM , Rating: 4
quote:
We can't transmit energy, so these things will have to use batteries or fuel.


Actually, if you ever get the interest to read up on the space elevator R&D on sites outside of Dailytech(*), the whole core and main basis they are betting the whole farm on for this technology is nanotubes.

The idea is with nanotubes you'd have the extreme strength, flexibility AND at the same time they would send power through the cable. Its been said that basically without nanotubes, the space elevator project will never be reality.

So then my assumption from all this is they actually are expecting to send power up so you won't need a self powered climber.

(*)Disclaimer: For the record, I'm not being sarcastic. I think your question/comment is valid - I'm merely reporting what I found out because of my own interest in this concept.



RE: Alternative solutions?
By guacamojo on 10/24/2006 9:55:17 AM , Rating: 2
quote:
We can't transmit energy, so these things will have to use batteries or fuel.


I'm not sure what you mean by this. A laser or a maser would transmit energy just fine. You would need a suitable receiving device on the climber, of course. (microwave antenna, photovoltaics...) Hence the goal of this competition.

Does anyone here know how well carbon nanotubes conduct electricity? Obviously if they're good conductors, you could create a circuit (basically 2 ribbons) to power the climber. Or potentially use maglev, although I wonder if that wouldn't make the ribbon even more complex and costly?



RE: Alternative solutions?
By Helbore on 10/24/2006 2:19:04 PM , Rating: 2
Carbon nanotubes have nearly no resistence, which means they are about the best possible conductor of electricity that we know of. One of the major ideas of the elevator is that the space station could house massive solar collectors and the energy gathered could be transmitted back down the cable to Earth. So, yeah, I can't see what the problem would be in supplying the vehicle itself with power. It should be dead easy.


RE: Alternative solutions?
By rushfan2006 on 10/24/2006 2:27:22 PM , Rating: 2
Well its not what *I* mean first of all, my post as just reporting what I found out - so its not my ideas or concepts its just repeating what I've read. However I think the idea is akin to an electric train - in this case you have whatever "powerplant" on the climber siphon power direct from the cable to power it.

I too also heard of the microwave idea as well though. And of course my only question with the power through the cable thing -- what kind of generator/power source at the anchor on earth do you need to give sufficient "juice" for a cable that is many many MANY miles in length?



RE: Alternative solutions?
By bupkus on 10/24/2006 9:59:36 AM , Rating: 2
Why not have the satelite roll up the tether pulling up the elevator? That way the tether gets shorter, reducing the weight, and no power needs to be transmitted? The initial rollout of the tether must start from the satelite anyway and the power source could be solar panels on the satelite.


RE: Alternative solutions?
By stromgald on 10/24/2006 11:19:31 AM , Rating: 2
You do realize that if the satellite tried to roll up the tether with a significant mass on the bottom end, the satellite would most likely drop out of orbit? The satellite can't just 'roll-up' the tether unless it had enough propulsion to keep it at a fixed altitude while the weight of whatever is at the bottom is pulling it down.

Although the propulsive force required doing it that way would probably be less than a normal rocket from the ground, it would also have to be very slow and the satellite on orbit would need a very large amount of fuel, making it very costly.

Its generally better just to have a counterweight up there and boost every once in a while than to have enough propellant on the satellite to pull something heavy up. I think most concepts put just a counterweight up there and the counter weight is reboosted by rockets/thrusters on each carrier. That way you don't need much propellant on the satellite


RE: Alternative solutions?
By exdeath on 10/24/2006 12:28:53 PM , Rating: 2
LOL

Where does that mass go exactly.. I'm curious...

500 lb satellite + 1000 lbs of free hanging tether below the satellite or a 1500 lb satellite because it’s carrying 1000 lbs of tether on it? Same tension in the remaining portion of the tether...


RE: Alternative solutions?
By lemonadesoda on 10/24/2006 7:22:23 PM , Rating: 2
LOL. 500lb on earth <> "500lb" in geostationary orbit. Also "g" changes, although not quite so fast as "weight".

While the OP suggestions have obvious criticisms, your reply has more! LOL


RE: Alternative solutions?
By exdeath on 10/24/2006 12:35:16 PM , Rating: 2
Did you mean the anchor satellite holding the tether on the top? With my first post, I thought you had meant the climber could roll up the cable as it climbed (which some have called satellite here).

Still, that won't achieve much. The limit is the tensile strength of the cable, and even if the anchor satellite could 'roll it up' to reduce the length, you still have the initial length, and now you are adding additional tension by winding it.

If you had the tensile strength to do that to begin with it wouldn't be necessary.


RE: Alternative solutions?
By exdeath on 10/24/2006 1:07:57 PM , Rating: 2
Just to show that:

T = force of tension in the cable
mg = force of the object on the bottom of the cable

At rest, T - mg = 0

If we wind the cable from the top, clearly T-mg > 0 because we have an accelerating mass, the system is no longer in rest, so we have a net force. If we consider the first several kilometers (since we have to get it off the ground initially), mg is a constant, and so the only place that extra force can come from is a larger T due to increased tension

So while you wind the cable, you relieve tension near the end of the trip, but at the cost of increasing it at the start. If the cable could handle the added tension of winding, it could just hang there freely and not need to be wound up in the first place.

The anchor satellite in geosynchronous orbit must handle the total mass of the full length of the cable, the climbing vehicle, and itself. This doesn’t change, ever.

With that, the higher the climber gets, the lower its mg gets due to getting further from the surface of the Earth. The more you wind the cable, not only do you have less total mass hanging on the cable, but you bring bottom end of the cable also higher off the surface of the earth, so the cable’s mg decreases as well. However the cable still has to have a tensile strength equal to the highest peak load that occurs at the start of the trip, and so must the satellite be able to handle the peak condition of a fully extended cable at the surface of the Earth with the vehicle suspended .00001mm off the ground.

A real problem directly related to your winding problem is this:

More interesting is the effect that Newtons 3rd law will have on the free floating satellite when a vehicle attempts to climb the cable. It will in effect, wind the cable from the ground as if to pull the satellite down (i.e.: picture that instead of the crawler climbing a stationary cable, that the crawler itself is stationary with its drive wheels pulling down on the cable and tugging on the satellite)

In order for the satellite to remain in orbit it must experience a net force of zero. As soon as you apply tension to the cable you have a net force down. Orbit parameters can be established to keep the satellite at rest with respect to the ground, including the mass of the hanging cable. Adding additional mass and tension will result in a net force that disrupts this rest state, and compensating for the non present payload in advance will have a net force on the satellite when there isn’t a load applied (think pulling a string with a force of 5 lbs to lift a 5lb weight, but the weight isn’t there all the time)

Clearly a reaction mass based propulsion system and fuel will be necessary on the anchor satellite itself to keep itself on correct orbit.


RE: Alternative solutions?
By exdeath on 10/24/2006 1:27:46 PM , Rating: 3
The alternative is to have a really *really* strong cable. Then you could put the satellite into an initial orbit that is NOT rest state. With the condition that the satellite is geosynchronous, a non rest state implies that only its altitude is changing, that is it’s either falling or climbing. Since we don't want it to fall, that can only mean the altitude is increasing, or rather it means the satellite is always at orbital escape velocity, kept at rest by only the tension forces in the tether.

If the initial tension is far greater in comparison to any payload, we can negate the long term cumulative effects of payload forces on the satellites initial acceleration.

So this doesn’t require fuel or propulsion on the satellite, but tethering a satellite to the Earth in orbit at escape velocity is why a very very very strong tether is needed.


RE: Alternative solutions?
By lemonadesoda on 10/24/2006 7:31:31 PM , Rating: 2
Very commendable additional comments. You deserve a medal for digging yourself out of that hole (your earlier post). But I bet you wish there was an edit or delete command on this forum ;-)


RE: Alternative solutions?
By Mclendo06 on 10/25/2006 1:49:04 AM , Rating: 2
You guys have some major misconceptions. Do you realize that you're are seriously underestimating the masses involved? The CG of the entire elevator system has to be maintained at geosync orbit - about 22,200 miles (35,800 km) in altitude above the equator. The tether runnnig along this entire distance is going to have some mass, say - optimistically, 100 lbm (pounds mass) per mile (3.1 slugs, or 45 kg) This will be under an acceleration varying from 1g at the surface to 0 g at the geosynchronous center of gravity. The total mass would be around a million kg of tether (2,200,000 lbm). Grossly approximating the weight (I don't want to do an integration after the test I took tonight), say that the overall weight behind held up by the tether at geosync orbit is the mass being accelerated by half a g - so about a million lbf (pounds force). Also, this is assuming you can make a tether that has a mass of 100 lbm a mile (equivilent to a titanium alloy cable with a radius of 56 thousandths of an inch) that can hold a million-lb tensile load, which you can't (the cable closer to the c.g. will have more under it to hold, therefore it will have to have a larger cross section, making it heavier). So in reality, even with the most exotic carbon nanotube composite tether you can come up to, you are still looking at total tether masses on the order of millions of lbs, probably more like tens of millions or more.

And on a side note, a space elevator would pretty much have to be "hung" from geostationary orbit. So you have to launch all this mass to a 22,000 mile orbit. At $10,000 a lb, that is going to make for a kind of expensive space elevator (not to mention that some forms of carbon nanotubes right now are a little more expensive to buy than it would cost to launch them into space - double ouch).


math?
By Lord Evermore on 10/24/2006 5:28:31 AM , Rating: 2
50 meters at 1 meter per second, and they made it in 58, how is that 2 seconds too long? Sounds like 8 to me.

And sure, 58 seconds would be great for 60 feet...but they only would have gone 50 feet, they'd still have to add time to go that extra 10 feet. Unless that's referring to the issue of it might have been a 60 foot climb due to stretching.




RE: math?
By Lord Evermore on 10/24/2006 5:30:25 AM , Rating: 1
Rereading it, they expected to climb 60 feet, that shouldn't have meant the climber went slower just because it was a shorter ribbon. If it went better than 1m/s on a 60 foot line, it should still go 1m/s on a 50 foot line.


RE: math?
By KristopherKubicki (blog) on 10/24/2006 5:36:24 AM , Rating: 2
From the videos I've seen of the other climbers, the velocity was not linear of the climbers.


RE: math?
By Visual on 10/24/2006 5:43:05 AM , Rating: 1
i'd assume the speed was not constant, it probably exceeded 1m/s but with a slow startup or speedup...
or its just a case of a dumb reporter...


RE: math?
By Spoelie on 10/24/2006 7:48:41 AM , Rating: 5
foot, feet.. what are you on man, it's all in meters...


RE: math?
By peldor on 10/24/2006 8:31:22 AM , Rating: 5
Maybe he wants a job a NASA.


RE: math?
By Spivonious on 10/24/2006 9:44:57 AM , Rating: 2
pwned!


RE: math?
By HueyD on 10/24/2006 8:45:07 AM , Rating: 2
I don't know much about the space elevator concept, but would'nt you have a problem with the cable snapping under its own weight? I mean we are talking about several kilometers of cable.


RE: math?
By guacamojo on 10/24/2006 9:47:14 AM , Rating: 2
Yeah, that's why the whole concept revolves around the ridiculously-high strength-to-weight carbon nanotube ribbon. From what I've read, the ribbon would be some 60,000 km long. Today's highest-strength steel or composite materials wouldn't get you within a factor of 100 of the performance requirements of a 60,000 km ribbon.

And according to at least one website, the "base tower" anchoring the ribbon would be about 50km tall. That's one TALL building.


RE: math?
By exdeath on 10/25/2006 10:27:31 AM , Rating: 2
Tower of Babel!

Hmm but then the main hull of the Eldridge is 26 miles
long, so the tower is only 41km ...


Space Elevator NOT a good idea
By TimberJon on 10/24/2006 11:33:37 AM , Rating: 2
Why? Stresses, like it stated. Why do you need an elevator? Why the need to raise cargo up out of our atmosphere without using NOX or whatever else, when you have fusion power on the way?

I say if there are any really governmental groups researching an orbital elevator (beanstalk) they should divert research time and money into developing a system of thruster ports and fusion engines for when the reactor becomes available and stable.

When that 400 seconds of plasma or so is achieved, unlimited power (based on size of the reactor) and thrust will be possible for a spacecraft, or cargoship for that matter.

While we wont have repulsors or anti-gravity, a ship will be able to lift off under its own power, making an elevator unnecessary.




RE: Space Elevator NOT a good idea
By Dantopia on 10/24/2006 12:19:54 PM , Rating: 2
Except that the space elevator will happen long before we achieve viable fusion power, especially on a scale of a spacecraft. The problem is also "specific impulse", not thrust... you have to have sufficient mass to eject out the back to create that thrust, hence a fusion rocket would still need significant amounts of non-nuclear "fuel" in the form of reaction mass. From what I've read, even a fusion powered rocket wouldn't be significantly better at lifting things into space than normal chemical rockets because of the weight of the reactor combined with reaction mass.

The space elevator can be made with refinements of current technologies, for relatively cheap in comparison to the time and effort required to develop fusion power. Sorry, you just aren't going to see "star trek" ships before this happens.


RE: Space Elevator NOT a good idea
By TimberJon on 10/24/2006 1:21:49 PM , Rating: 2
good point. But you wont need alot of reaction mass on a fusion powered ship as you said.

The specific impulse of the current rocket we use has an SI of 450 seconds. Pound of fuel = pound of thrust for 450 seconds.

The minimum specific impulse of a fusion engine would be roughly 120,000 seconds. So you could lift off of earth and go to the moon and back on a gallon or two of liquid hydrogen. convert it to gas and mix it to the reaction within the engine, at the front cone.

Hydrogen would be your reaction mass, and you could scoop it up or collect it from another atmosphere, or our own, by skimming the surface. OR bottle it up and have it sent to a local pickup point. Like oversized CO2 bottles for air guns.

I dont want star trek ships, theyre unrealistic.

This orbital tether/beanstalk is a bad idea. Too many factors and stresses on the system.

http://answers.yahoo.com/question/index;_ylt=Aiz70...

If they make the tether, great. Will it work? who knows. Hope it doesnt malfunction, or fall.


RE: Space Elevator NOT a good idea
By Dantopia on 10/24/2006 4:26:57 PM , Rating: 2
I'm not sure where you got the 120,000 seconds for the SI of a fusion powered ship though.

They already have designs for a fission nuclear rocket, using thermal hydrogen... it has an estimated SI of 1000-2000 seconds depending on the design of the core. I know fusion is more efficient than fission, but if fission (which is 10^7 times more energy than chemical) can only increase the SI by a little, then changing to the more efficient fusion won't increase it enough to matter. You still need an awful lot of hydrogen to throw out the back.

http://en.wikipedia.org/wiki/Nuclear_thermal_rocke...


Zap!
By WxGuy192 on 10/24/2006 12:48:55 PM , Rating: 2
It'd be interesting to see one of these space elevators when a thunderstorm moves near it. Many thunderstorms have electric fields on the order of 150-400kv/m, and it'd be interesting to see what happens to the well-conducting nanotube in that environment. Planes can initiate lightning, and I'd imagine we'd see something similar with the space elevators (though they'd be grounded, so the elevator would act like a giant charge drain). Then again, nanotubes are very small relative to the areal extent of thunderstorms. Regardless, current flow in lightning channels (particularly positive-flash CG) is / can be on the order of 10s to 100s of amps, which seems to be an awful lot for a tiny tube.




RE: Zap!
By lemonadesoda on 10/24/2006 7:39:28 PM , Rating: 2
This would create an interesting powersource for the climber. Speed him up a bit, I guess. LOL

Actually, that's a nice point. If you could safely harness the 150+kv/m, you could probably put quite a few kg into space. Bio power.

Some kind of sectional polarisation could be used to create an "electro-magnetic pump" in the interior of the carbon nanotube (or hollow cylinder constructed of carbon nanotubes). The acceleration forces would be rather nasty (explosive in fact), so some additional thought is needed before using it to ship biological materials.


.
By bbomb on 10/24/2006 2:39:04 PM , Rating: 2
Ok maybe i'm just retarded but what exactly do we ended to attach the other end of the tether to? Im assuming that in this case it was just held up with a crane or something?




RE: .
By Eris23007 on 10/24/2006 6:51:48 PM , Rating: 2
A satellite stays in orbit at a certain altitude because once it reaches a certain velocity, its outward force matches the inward force of gravity. There is a precise altitude where the velocity necessary to maintain a constant altitude results in the satellite having an orbital period the same as the earth's rotational period. This is known as geosynchronous orbit, and occurs at a radius of 26200 miles from the center of the earth. If it holds position above a certain point on land, it has no orbit inclination and is known as geostationary - the satellite does not move relative to a point on ground - it appears to "hang" in the same position all the time, directly above the equator. This is where most telecom satellites (such as DirecTV or Dish Network) satellites reside.

The concept of a tether is a foundational principle in orbital mechanics. It works for the same reasons as those described above - if you have two objects of equal mass connected by a wire, their orbit will be at a velocity determined by the center point of the wire. If you have unequal masses, the orbit velocity will be determined by the weighted average point. This is how the space elevator is designed to work: hang an enormous mass large enough to offset the weight of the entire 22,236 miles of nanotube cabling (to sea level)just beyond the geostationary orbit, such that the orbit point is at geostationary precisely. The elevator cable will appear to be stationary from the ground perspective, but from an external observer, it would appear as if the mass was whipping around the planet at a remarkably high rate, in order to maintain position above that one point on earth.

To address another individual's question: the folks who are studying the Space Elevator concept have already found a spot on the equator (necessary to be geostationary) in the middle of the pacific ocean that has remarkably low average lightning activity. There are a number of concepts as to how to handle the end of the cable that hangs down to earth. Some think anchors should be drilled into the ocean bedrock; others believe you don't need to anchor the elevator at all...


Hey
By Burning Bridges on 10/24/2006 3:33:23 AM , Rating: 2
At least they know the length of the ribbon now, right?

Didn't they have to take it down to measure it at one point?




Don't trust journalism
By jmunjr on 10/24/06, Rating: -1
RE: Don't trust journalism
By ted61 on 10/24/2006 10:19:55 AM , Rating: 2
From reading the links, it looks like the tether stretched during the event. They didn't know how long the tether was until it was measured again. I would guess that it started at 50 meters and stretched to 56 meters to make the 58 seconds two seconds slow.


RE: Don't trust journalism
By TimberJon on 10/24/2006 11:35:42 AM , Rating: 2
I thought i read somewhere that the actual tether would be made of nanotubes, or nanofibers, because of the linkages in the chemical structure. Something about it being much stronger than conventional cables and the like.


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